Great news! If you find the silicon lifts after a while you may find that 3M VHB tape holds. I’ve used it to stick some small skegs to the underside of my Adventure hull and it has become a permanent bond. Proper hull prep with alcohol and flaming are very important. More info here:
https://www.hobie.com/au/en/forums/view ... 8&start=15I’m down Gosford way and probably won’t be back up your way any time soon. I use Navionics on a Samsung Tablet or a Garmin etrex30 gps, save the track as a kml file in Garmin Basecamp and export that to Google earth.